Differential diagnosis of nonclassical 21-hydroxylase deficiency and polycystic ovary syndrome

Objective To explore the differential diagnosis methods between nonclassical 21-hydroxylase deficiency(NC21-OHD) and polycystic ovary syndrome(PCOS). Methods The clinical data of 31 women with NC21-OHD were compared with those of 29 women with PCOS. Results Women with NC21-OHD showed a higher prevalence of adrenal hyperplasia and lower likelihood of polycystic ovary(PCO) than those with PCOS(P<0.05), with lower height(P<0.05). The levels of adrenocorticotropic hormone (ACTH), 17-hydroxyprogesterone(17-OHP), androstenedione(AD), total testosterone(TT), and progesterone were higher in women with NC21-OHD compared with those with PCOS(P<0.05). Women with PCOS had higher levels of luteinizing hormone(LH) and higher ratio of LH to follicle stimulating hormone(FSH) than those with NC21-OHD(P<0.05). The best two identification indexes for the two diseases were 17-OHP and progesterone, with the optimal cut-off points 3.34 ng/ml(sensitivity 89.7%, specificity 93.1%) and 0.64 ng/ml(sensitivity 90.0%, specificity 75.9%), respectively. During the 1-day mid-dose dexamethasone suppression test(DST), women with NC21-OHD had higher inhibition rates of 17-OHP, progesterone, AD, and TT(P<0.01) than those with PCOS. Their optimal cut-off values of suppression rates were 73.5%(sensitivity 95.2%, specificity 100.0%), 55.5%(sensitivity 100%, specificity 88.9%), 61.4%(sensitivity 84.2%, specificity 100.0%), 68.3%(sensitivity 65.0%, specificity 100.0%), respectively. Conclusion The clinical manifestations of women with NC21-OHD are similar to those with PCOS. 17-OHP is the best differential indicator and the 1-day mid-dose DST plays an important role in the identification of the two diseases. Genetic analysis is the gold standard for distinguishing the two diseases. Key words: Nonclassical 21-hydroxylase deficiency; Polycystic ovary syndrome; 17-hydroxyprogesterone; Progesterone; Dexamethasone suppression test